Introduction:
Research on the association between neighborhood environments and systolic blood pressure (SBP) is limited, predominantly cross-sectional, and has produced mixed results. Investigating specific aspects of neighborhood environments in relation to changes in SBP may help to identify the most important interventions for reducing the population burden of hypertension.
Hypothesis:
Better neighborhood food, physical activity, and social environments will be associated with lower baseline levels of SBP and smaller increases in SBP over time.
Methods:
The Multi-Ethnic Study of Atherosclerosis recruited participants from six sites in the U.S., aged 45-84 (mean 59) and free of clinical cardiovascular disease at baseline. Those with non-missing data for key variables were included (N=5,997); the analytic sample was 52.5% female, 39.1% White, 27.3% Hispanic, 11.9% Black, and 21.7% Chinese, with median follow-up time of 9.2 years (IQR 4.5) and SBP measured at three or more exams for 91.3% of participants. SBP in subjects taking anti-hypertensive medication were replaced with multiply imputed estimates of unmedicated SBP, imputed at each exam. Summary measures of neighborhood food and physical activity environments incorporated survey-based scales (healthy food availability and walking environment) and GIS-based measures (density of favorable food stores and recreational resources). The summary measure of the social environment combined survey-based measures of social cohesion and safety. Neighborhoods were defined by a one-mile buffer around each participant’s home address. Linear mixed models were used to model associations of time-varying cumulative average neighborhood environmental summary measures with SBP over time, adjusting for individual-level covariates (demographics, individual- and neighborhood-level SES); models with and without adjustment for baseline SBP were used to evaluate associations of neighborhood environments with SBP trajectories.
Results:
In models mutually adjusted for all three neighborhood domains and covariates, living in a better physical activity environment was associated with lower SBP at baseline (-1.34 mmHg [95% CI: -2.24, -0.45] per standard deviation higher cumulative average physical activity summary score), while living in a better social environment was associated with higher SBP at baseline (1.00 mmHg [0.39, 1.63] per standard deviation higher); food environment scores were not associated with baseline SBP. After adjustment for baseline SBP, there was no association between any neighborhood environments and trajectories of SBP.
Conclusions:
Better food and physical activity environments were associated with lower baseline SBP, while better social environments were associated with higher baseline SBP. Neighborhood environments appear to have minimal direct effect on SBP trajectories.
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